Snap bone back to an offset relative to another bone
Consider adding another Child Of constraint, but put this one on the hand itself, and for the target, make an empty or bone that has been placed near the hand rest position (and which is also parented to the gun). Keyframe the influence slider for this &quot;hand rest&quot; Child Of constraint so that the slider is in the fully off position when the hand is currently reloading, and then keyframe the same slider so that it is fully on when the hand needs to be at full rest under the gun. The influence slider will interpolate smoothly when keyframed, so the hand will gradually become more and more the child of the empty or bone under the gun as time progresses. If this looks wonky animation-wise, you could leave the influence off until you have keyframed the arm manually returning to the gun, at least until the hand is very near to the gun. Then you could keyframe the Child Of constraint influence slider to be fully on only at that point. You will still get the advantage of knowing for sure that the hand will end up in the final rest position, where it belongs.